Ham Radio / Off-grid communication

It's not the open-source part that bugged them, their argument was that it was detrimental to the hobby because you "only can copy-paste code from Internet and understand nothing" and it was not "REAL code".

I think that Arduino is a great gateway into electronics and microcontrollers, this argument is unfathomably retarded. But there's only so much you can argue with someone who can only retort "YES IT DOES".

While the majority of the older hams in my club are patient and eager to share what they know, some think they have some kind of parental or elder "authority" because they are 20+ years older than you, which I find very irritating. In general, it's the same old farts that rant against digimodes to no end.

My opinion is that there is not enough left of us to infight. Even if younger hams are starting to come in, the mean age is dangerously increasing. I'll wait the bad apples out.

Looking forward, after repeater maintenance, we'll fuck around a bit with LoRa on 433 MHz (APRS and Meshtastic). Not something I would have played with on my own, but I'm looking forward to try this out with my local hams.
 
Juan Números said:
It's not the open-source part that bugged them, their argument was that it was detrimental to the hobby because you "only can copy-paste code from Internet and understand nothing" and it was not "REAL code".
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That's weird since my impression of mainstream hams these days is they just want to buy a rig and work contacts/do 'activations'.
 
Dark Macca said:
►Part 2 will go more in-depth with VHF / UHF communications and cover long distance HF communications
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► I'M RETARDED HOW DO I GET INTO RADIO? Part 2 - HF Edition


1. Introduction

HF, or the High Frequency portion of the radio spectrum (3 to 30 MHz) allows you to communicate with people who are further than line of sight using something called ionospheric propagation. The ionosphere is a layer of the earth's upper atmosphere that has special properties that allow for electromagnetic waves, in this case, your radio signals to travel across it.
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HF communications involve a little bit more setup then what you would find with something like a handheld VHF / UHF radio. But it allows for communications to take place across continents and vast distances that otherwise wouldn't be possible through line of sight.

Different parts of the HF spectrum exhibit different properties. That means that a signal on one frequency might propagate differently than a signal on transmitted on another. This can be used to your advantage in your communication plan.

The HF spectrum is segmented into "bands", which are referred to by their wavelength in meters. For example 7.0 - 7.3 MHZ is the 40 meter band. Each band has it's own unique characteristics of how radio waves propagate over short and long distances. These differences are influenced by factors such as time of day, solar activity, and atmospheric conditions.

Below is a table that serves as a general introduction to some of the bands.
10 meters28.0 - 29.7 MHzDuring high solar activity this band is open for short periods, allowing for long distance (DX) communications for voice, CW, and data. Very unreliable however.
20 meters14.0 - 14.35 MHzOpen mostly year round in this current solar cycle for evening long distance communication
30 meters7.0 - 7.3 MHzA good band for CW and digital modes with DX propagation during the day.
40 meters7.0 - 7.3 MHzGood for daytime regional propagation. Towards the night when the sun sets,the band opens up for DX communications.
60 meters5.3 - 5.4 MHzSimilar properties to 40 meters, but the best band for regional communication through skywave propogation. ** Note: In many countries including the United States, this band has channels you must adhere to.
80 meters3.5 - 4.0 MHzNighttime skywave propagation is good for regional communications. Daytime signals are mostly ground wave, with certain exceptions in higher latitudes.

There are websites that track solar and propagation conditions such as the solar data widget provided by N0NBH, showing you what bands are open during what time of day.
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Brief intro to HF antennas
As you move further down the bands, the physical space and requirements for an antenna increases. Lower frequency bands such as 40 meters and 80 meters, typically require much larger antennas and a higher point for them off the ground. This is one of the drawbacks to HF.

When most people think of an antenna, they think of something like this:
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While this is an antenna, the resonant band or frequency is significantly higher than those found in the HF range. HF antennas require larger footprints and more physical space because of the longer wavelengths they operate at. For example, a WiFi antenna may be designed for 2.4 GHz, whereas most HF communications occur in the 3 to 30 MHz range. For an antenna to be resonant, it needs to have an electrical length that matches a multiple of half or quarter wavelengths of the frequency it's designed for.

The most common type of antenna is the standard half-wave dipole. A dipole is simply two conductive elements like a wire connected to the radio's feedline in the center. Each of the elements is typically one-quarter wavelength long, resulting in a total length of half a wavelength. For example, a half-wave dipole for the 40-meter band would be about 20 meters (66 feet) in total length. The dipole is usually strung horizontally and needs to be elevated at least a quarter wavelength off the ground for effective performance.
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There are also other designs such as the end-fed half wave, which use one wire, a counterpoise, and a transformer (usually 49:1) at the feedline.
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If you want a good primer that goes into more detail and explains these concepts better than I can, this video from Rhode & Schwarz is an excellent explainer:
The three most common types of signals on HF are voice (SSB), Morse code (CW), and data modes like FT8 and JS8Call.

Single Side Band (SSB) is used for voice communications. Typically upper sideband (USB) is used above 10 MHz and lower sideband (LSB) is used below 10 MHz. This is more of a general rule followed in most bandplans, with the only difference between USB and LSB being which side the carrier is on.
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Morse code, or CW is one of the best ways to get signals heard, even on extremely low power and in extremely poor conditions. It's the most versatile communication tool as it can be done by a sufficiently trained operator without any external tools or a computer. CW requires significant practice for both listening and transmitting.
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2. Radios

HF radios tend to cost more than a simple handheld. with price ranges between $500 to $2000 USD. Unfortunately there are few options from the big name manufacturers (Icom, Yaesu, Kenwood) that are affordable.

The radio I recommend for getting started with HF is the Xiegu G90. It is a fantastic rig that costs around $400 USD
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The G90 has 20 watts of transmit power and a built in tuner. As someone who has purchased more than a dozen of these rigs I have never once had a problem with them. They are solid and reliable and you can't get much better of a starter rig than this one.

The G90 is capable of doing voice (SSB), morse code (CW), and Digital modes like FT8 and JS8Call when connected to a computer.

3. Getting on the air, basic setup with the G90
I realize that while writing this it's very hard to condense everything there is to know in a single post. So I'm going to provide a "starter setup" for getting on the air.

The radio I recommend is the Xiegu G90. The G90 requires a 12 volt external power supply that can be provided by a lithium phoshpate or lead acid battery. You'll want one that's rated for 10 to 20 Amp hours. A 20 Amp hour LiFePo4 battery can supply the G90 with power for around 4 hours with moderate use. You can also use a desktop power supply that's rated for 12 volts @ 30 continous amps when you have access to mains power.

The G90 will come with a power cable with unsoldered leads. You can crimp d-ring connectors or Anderson powerpoles onto these.

The next thing you'll need after getting your power setup is coax for your antenna. The G90, and most HF rigs use a type of connector called a PL-259 plug. There are different types of cable but all are universally 50 ohm. RG-58 is usually the cheapest option.

Once you've got your radio, power, and coax all set up the last thing you need is an antenna. The antenna will be dependent on what bands you plan to use which is determined by who you want to communicate with.

A useful tool for figuring out propagation conditions is VOACAP. You simply pick a start and end point, and plug in your details on the right hand panel. This will show you a simulation of what bands will allow you to facilitate communications of your mode between Point A and Point B, which represents a circuit.
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The chart you will want to look at is REL (Reliability), which in simple terms is if your signal will be heard. These percentages are graphed on the X-axis by hour of the day from 00h to 24h in UTC.

From this chart, you can see that the 30 meter band is open most of the day, while 60 meters covers the circuit during the night.

An antenna like a linked dipole can cover multiple bands and is what I'd recommend in this scenario. An end-fed halfwave with a 49:1 transformer plus your radio's built in tuner would also be able to cover these bands as well.

 
Average 7200 kHz experience:
 
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I was only just informed that this thread, and I’ve just bought a Xiegu G90. Waiting for the computer interface to get here, though. I have tested it a bit snd it seems to work. Im excited to finally have a HF rig.
 

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Give me an idea for some 3d printable multiband antenna for my RTL-SDR setup.
I'd love to have a takedown capable dealio made out of household bullshit and printable.

I want to combine both autistic hobbies if possible.
 
Rekeita's Kidneys said:
Give me an idea for some 3d printable multiband antenna for my RTL-SDR setup.
I'd love to have a takedown capable dealio made out of household bullshit and printable.

I want to combine both autistic hobbies if possible.
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It’s not really 3D printable, but what about the dipole kit that you can get with the RTL-SDR? These are fairly versatile.
 
Maori Kiwifruit Growers said:
Ham radio is the last wild place, which is funny because you need a government license.
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Only because the League of Unextraordinary Gentlemen and the big three equipment manufacturers need that facade of the amateur radio service being highly regulated so that they can keep charging League members for practically nothing and selling overpriced junk to people who haven't figured out that you don't need to spend what Kenwood, Yaesu and Icom really want to charge you to be able to put out a decent signal. You actually have a better quality of people on the Citizens Band that has been all but abandoned as far as enforcement goes for decades. But Riley wants to keep telling people, as he has for nearly thirty years, that the amateur radio spectrum is especially sought-after and if we talk politics on air we're going to lose it altogether. He's literally been attempting to scare people into believing that since he went after the "Liberty" Net back in the mid-90s.
 
Bit of a PSA for G90 owners: if you plan on using stuff like FT8, or other stuff where there’s full transmit power, it may cause the output chip to overheat and possibly fry. There is a thermistor that’s supposed to counter this, but it’s nowhere near in contact with the chip. You probably should get some silicone putty or whatever and glue the probe down to the chip. You can just barely get it in contact if you bend the probe legs a little bit. I’m gonna buy some putty tomorrow and fix mine.

It’s difficult to see but the thermistor is nowhere near the chip, it’s got a solid mm or two of air between them.

The place I bought it from actually gave me permission to open up the radio despite there being a warranty sticker, and he was curious to know if the problem had been fixed in my revision (mine was made on the 30th week of 2023). Very kind of him to trust my judgement and keep the warranty for me, especially since I paid to have extended warranty.
 

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Doggo said:
Bit of a PSA for G90 owners: if you plan on using stuff like FT8, or other stuff where there’s full transmit power, it may cause the output chip to overheat and possibly fry. There is a thermistor that’s supposed to counter this, but it’s nowhere near in contact with the chip. You probably should get some silicone putty or whatever and glue the probe down to the chip. You can just barely get it in contact if you bend the probe legs a little bit. I’m gonna buy some putty tomorrow and fix mine.

It’s difficult to see but the thermistor is nowhere near the chip, it’s got a solid mm or two of air between them.

The place I bought it from actually gave me permission to open up the radio despite there being a warranty sticker, and he was curious to know if the problem had been fixed in my revision (mine was made on the 30th week of 2023). Very kind of him to trust my judgement and keep the warranty for me, especially since I paid to have extended warranty.
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Is that black stuff under the transistors the chassis or something? Because if they're not heat sinking those transistors, then, well. Sigh.
 
Mikoyan said:
Is that black stuff under the transistors the chassis or something? Because if they're not heat sinking those transistors, then, well. Sigh.
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I believe so. It seems the transistors bolt down into the bottom case.
 
They are reverse mounted, started as a trick to cheapen chinese production and worked well enough you can find it everywhere now. You don't need special heatsinks that way and can use chassy etc as a HS
 
Dawdler said:
They are reverse mounted, started as a trick to cheapen chinese production and worked well enough you can find it everywhere now. You don't need special heatsinks that way and can use chassy etc as a HS
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Heatsinking off the chassis is fine, I'm just trying to figure out where they went wrong. Guess just underspecced parts.
 
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